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Lateral view of a Male Baetis (Baetidae) (Blue-Winged Olive) Mayfly Dun from Mystery Creek #43 in New York
Blue-winged Olives

Tiny Baetis mayflies are perhaps the most commonly encountered and imitated by anglers on all American trout streams due to their great abundance, widespread distribution, and trout-friendly emergence habits.

Case view of a Pycnopsyche guttifera (Limnephilidae) (Great Autumn Brown Sedge) Caddisfly Larva from the Yakima River in Washington
It's only barely visible in one of my pictures, but I confirmed under the microscope that this one has a prosternal horn and the antennae are mid-way between the eyes and front of the head capsule.

I'm calling this one Pycnopsyche, but it's a bit perplexing. It seems to key definitively to at least Couplet 8 of the Key to Genera of Limnephilidae Larvae. That narrows it down to three genera, and the case seems wrong for the other two. The case looks right for Pycnopsyche, and it fits one of the key characteristics: "Abdominal sternum II without chloride epithelium and abdominal segment IX with only single seta on each side of dorsal sclerite." However, the characteristic "metanotal sa1 sclerites not fused, although often contiguous" does not seem to fit well. Those sclerites sure look fused to me, although I can make out a thin groove in the touching halves in the anterior half under the microscope. Perhaps this is a regional variation.

The only species of Pycnopsyche documented in Washington state is Pycnopsyche guttifera, and the colors and markings around the head of this specimen seem to match very well a specimen of that species from Massachusetts on Bugguide. So I am placing it in that species for now.

Whatever species this is, I photographed another specimen of seemingly the same species from the same spot a couple months later.
27" brown trout, my largest ever. It was the sub-dominant fish in its pool. After this, I hooked the bigger one, but I couldn't land it.
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Willmilne has attached this picture to aid in identification. The message is below.
Manitoba Canada

Posts: 19
Willmilne on Jul 3, 2008July 3rd, 2008, 10:38 am EDT

Found some of these lovely nymphs while out - any suggestions as to species?



Site Editor
"Bear Swamp," PA

Posts: 1681
GONZO on Jul 3, 2008July 3rd, 2008, 12:04 pm EDT
My first impression is that it is a Maccaffertium (formerly Stenonema) nymph. That said, however, you have some heptageniids up there with which I am not at all familiar. It is a very striking specimen and ripe to hatch (a "blackwing"). Perhaps Roger or Konchu can offer another opinion.
Taxon's profile picture
Site Editor
Plano, TX

Posts: 1311
Taxon on Jul 3, 2008July 3rd, 2008, 7:15 pm EDT

These are the two Heptageniid nymphs on Will's website. I arranged them similarly aligned for comparison purposes.

In late May, I suggested the one on the left was probably Leucrocuta maculipennis. My guess is that the one on the right may be either Heptagenia flavescens or Maccaffertium modestum. How's that for hedging?

In any event, Will certainly does have a talent for photographing aquatic insects.
Best regards,
Roger Rohrbeck
Manitoba Canada

Posts: 19
Willmilne on Jul 4, 2008July 4th, 2008, 3:39 am EDT
Thanks for the suggestions on ID.So much to learn. I guess I have to start learning to photograph the key details and get a little more focused. I am at the moment simply taken with the beauty and subtle variations of color in these, sometimes at first glance , rather drab looking insects. Glad you are enjoying the pics Roger.

Would you think this is the same species at a different stage, the markings are very similar - it was collected at the same time. Much lighter and more yellow olive in tone and lacking the lower leg banding.



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"Bear Swamp," PA

Posts: 1681
GONZO on Jul 4, 2008July 4th, 2008, 6:10 am EDT

The photo in the link does appear to be the same species, but not as "ripe" yet. Overall, I am leaning toward a Maccaffertium ID because the gills look more like that genus than Heptagenia to me.

By the way, I came across a recent article in the Journal of Insect Science that proposed a new species, Heptagenia whitingi (considered a sister taxon of H. flavescens). The dorsal photo included in the article appeared to match the markings of your other specimen (the one on the left in Roger's comparison) almost exactly, except that it is a paler version (probably due to preservation in alcohol). What first caught my attention was the mention of the large, pale rectangular markings on abdominal tergum 4 as an important diagnostic character. (However, please note the comment about H. adaequata in the larval diagnosis.) The other interesting aspect was the use of DNA "barcoding." It's just a thought, but you can find the article at:


(I wish I could make that a direct link, but I can't seem to get BBCode to work here. My computer skills suck, so I'm probably doing something wrong.)
Avondale PA

Posts: 2
Dhfunk on Nov 15, 2008November 15th, 2008, 5:51 am EST
H. whitingi seems reasonable for the one on the left. The one on the right looks a perfect match for Stenonema femoratum. If you were to flip the specimen over and find a series of dark sublateral spots on each side of the abdominal segments, that would nail it.
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"Bear Swamp," PA

Posts: 1681
GONZO on Nov 15, 2008November 15th, 2008, 7:30 am EST
Nice of you to pick up on this one, David. I sometimes forget to consider femoratum now that it is stranded on its own. The illustration in Spieth (of "S. femoratum tripunctatum," 1947) and especially the photo in Lewis (of "S. tripunctatum," 1974) do look very much like Will's other specimen. Thanks for pointing things in the right direction!

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